1. Field of the Invention
The present invention relates to a control adjustment method for a reproduction/recording apparatus for a disc-shaped recording medium which performs real-time reproduction/recording of audiovisual (AV) data, such as television broadcasting. The present invention also relates to a reproduction/recording apparatus for a disc-shaped recording medium.
2. Description of the Related Art
Optical discs are now available as reproduction/recording mediums used in reproduction/recording apparatuses, such as optical disc video recorders. Data is reproduced from or recorded to an optical disc by focusing light which is emitted from a semiconductor laser onto an information surface of the disc so that the light converges on a micro-scale spot with a diameter of 1 micron or less. As a high-density, mass storage recording medium, such an optical disc has random access characteristics better than that of conventional tape media. In addition, a noncontact reproduction/recording using a laser beam reduces deterioration due to repeated use, thereby enabling disc manufacturers to mass-produce low-cost duplications by means of mastering.
CDs are an example of optical discs, which has replaced the conventional analog record and has become popular as a high quality-sound digital audio medium. Also in recent years, DVD has been commercialized as a high quality digital image-recording medium. In view of these trends, it is predictable that optical discs will develop further in the future as digital recording media for AV data.
CDs and DVDs are reproduction-only optical discs, on which data is pre-recorded. On the contrary, recordable optical discs have been developed in recent years, on which users can record AV data at home. An example of such an optical disc is DVD-RAM. Furthermore, in order to reproduce/record television programs, for example, from/to these recordable optical discs apparatuses such as optical disc video recorders are now under development. These video recorders are now regarded as novel products which will replace conventional video tape recorders such as VHS.
For such a reproduction/recording apparatus for performing noncontact recording/reproduction and capable of high density recording, it is indispensable to employ: a tracking control technique for making the laser beam stably follow lands or tracks provided in advance on the media; a focus control technique for forming the micro-scale spot; and a laser power control technique for achieving a laser output with a stable power. As the recording density becomes higher, more accuracy is required for these techniques.
In order to improve the accuracy of the aforementioned control techniques, control adjustments have been incorporated into the reproduction/recording apparatuses, in order to adjust the control of the reproduction/recording apparatuses in response to environmental changes such as a temperature change inside the reproduction/recording apparatus. According to such a control adjustment, when the temperature inside the apparatus changes, a process of control adjustment in response to the ambient temperature around or the internal temperature inside the apparatus is performed, even in recording or reproduction, so that the control corresponds to the changes in circuit characteristics and the output power of the semiconductor laser, which depends on temperature. By performing such a control adjustment, a more accurate control is achieved.
The above control adjustment method regarding temperature change will now be described in detail with reference to FIGS. 1 to 3.
FIG. 1 is a plan view of the recording surface of an optical disc 100, which is a disc-shaped recording medium. The optical disc 100 is provided thereon with a data region 101 and a lead-in region 102. The data region 101 includes regions for recording audiovisual (AV) data, and the lead-in region includes control tracks for recording disc management information and a test region 104 for performing control adjustments. Although not shown in FIG. 1, a plurality of tracks for recording data are formed on the recording surface of the optical disc along circumference direction. Each track is divided into a plurality of sectors, each of which is the basic unit for data reproduction/recording.
An example of AV data to be recorded on the data region 101 is program information such as a TV broadcast. On an optical disc capable of random access, a single program may be divided into a plurality of portions and recorded to a plurality of regions as a result of repeated recording and deleting. For example, FIG. 1 shows a case where a single program information is recorded to three regions 103a, 103b, and 103c. 
Data recording to the optical disc of FIG. 1 will now be described.
Data a to be recorded is first recorded to the region 103a, thereby becoming recorded data a. The next data is recorded to the region 103b, and in order to achieve this recording, an optical head for recording, which is provided in the reproduction/recording apparatus, has to be moved from the region 103a to the region 103b. This is called a seek operation. Herein, the term xe2x80x9cseekxe2x80x9d includes not only the movement of the optical head to a target track for reproduction/recording but also the holding of the optical head until the target sector reaches the optical head by the disc rotation. Furthermore, in the case of a CLV method or a ZCAV method, in which the rotation speed of the disc is changed for the reproduction or recording, the term xe2x80x9cseek periodxe2x80x9d means not only the time required for the seek operation as described above but also the time required before the next reproduction/recording can be performed. This includes the setting time before the rotation speed of the disc motor reaches an appropriate speed for reproduction/recording.
After the execution of the seek operation, data b to be recorded is recorded to the region 103b, thereby becoming recorded data b. Next, the seek operation from the region 103b to the region 103c is performed, and the data c to be recorded is recorded to the region 103a, thereby becoming recorded data c. Accordingly, seeks and recordings are repeated so as to divide and record continuous single AV data to a plurality of regions.
The data to be recorded during the seek operation is temporarily stored in a semiconductor memory of the reproduction/recording apparatus, and then recorded to a recording region after the seek operation is completed. FIG. 2 is a buffer model illustrating the quantity of data temporarily stored in the semiconductor memory during the recording of the data a, b, and c, to the respective regions 103a, 103b and 103c. In FIG. 2, the horizontal axis represents time and the vertical axis represents the stored data quantity.
During the period 201, the data a is first recorded. The data is recorded at a faster speed than the data generating speed, and therefore the quantity of data stored in the semiconductor memory decreases. Eventually, the data is recorded immediately after it is generated. After the data a is recorded, a seek operation for recording the data b is performed during the period 202. During the seek operation, a data recording on the disc is impossible, and therefore all of the generated data is temporarily stored in the memory, and the stored data quantity increases. When the seek is completed, the stored data quantity reaches the maximum value A in FIG. 2.
After the optical head reaches the region 103b for recording the data b, the data stored during the seek period 202 is recorded, as well as the data b, in the period 203. The data is recorded at a faster speed than the data generating speed, and therefore the quantity of data stored in the semiconductor memory decreases. Eventually, the stored data quantity is close to zero, and thereafter the data is recorded almost immediately after it is generated.
In the period 204, a seek operation for recording the data c is performed, as in the seek period 202 for the data b. During the period 204, a data recording on the disc is impossible, and therefore all the generated data is temporarily stored in the memory and the stored data quantity increases. As in the period 203 for recording the data b, the data stored during the seek period 204 is recorded, as well as the data c, in the period 205. The data is recorded at a faster speed than the data generating speed, and therefore, the quantity of data stored in the semiconductor memory decreases. Eventually, the stored data quantity is close to zero, and thereafter the data is recorded almost immediately after it is generated.
In the above case where the seeking recording are merely repeated, the data transmitted during the seek operation can temporarily stored in the memory by providing the reproduction/recording apparatus with a semiconductor memory capable of storing data larger than the data generated during the maximum seek duration. This makes it essentially possible to perform, real time continuous recording of the AV data even though it is actually a split recording divided by seek operations. In FIG. 2, the maximum value of the data stored in the memory is represented by A. For example, when the maximum seek duration is one second and the data generating speed is 10 Mbps, the stored data quantity will be 10 Mbit. Therefore, by using a semiconductor memory having a capacity larger than this quantity, a continuous recording of AV data is achieved.
A control adjustment method for a conventional reproduction/recording apparatus will now be described. According to the conventional control adjustment, the temperature inside the apparatus is first measured, and if the temperature change detected is equal to or more than a predetermined value, a control adjustment is requested. In the conventional example, a control adjustment is conducted immediately after the request. FIG. 3 is a buffer model of the conventional control adjustment during recording. In this model, the control adjustment is conducted based on the control adjustment request addressed with the worst timing, i.e., immediately after a seek. In FIG. 3, the horizontal axis represents time and the vertical axis represents the stored data quantity.
During the period 301, the data a is first recorded. The data is recorded at a faster speed than data generating speed, and therefore the quantity of the data stored in the semiconductor memory decreases. Eventually, the data is recorded in the disk almost immediately after it is generated.
After the data a is recorded, a seek operation for recording the data b is performed in a period 302. During the period 302, a data recording on the disc is impossible, and therefore all of the generated data is temporarily stored in the memory and the stored data quantity increases. When the seek is completed, the stored data quantity reaches the maximum value A as shown in FIG. 3.
A control adjustment request is addressed at the time 307 when the period 302 is over (i.e., immediately before the start of the recording of the data b). According to the conventional example, a control adjustment is conducted immediately after a control adjustment request is addressed. Therefore, the control adjustment begins immediately after the time 307.
The control adjustment is performed in the following manner. For example, in the case where the recording power of the laser used for the recording is adjusted, the optical head is moved from the data region 101 for data recording to the test region 104 provided at the innermost periphery (or the outermost periphery) of the optical disc as shown in FIG. 1. Then, by experimentally recording and reproducing test data while changing the recording power by small amounts, the most suitable recording power corresponding to the current temperature is detected. A circuit constant of the reproduction/recording apparatus is adjusted based on the detected most suitable recording power, and the recording thereafter is performed by the most suitable recording power.
During the control adjustment, a data recording on the disc is impossible, and therefore all of the generated recording data is temporarily stored in the memory and the stored data quantity increases as shown in FIG. 3. After the control adjustment is performed, the second seek (not shown) is conducted for returning the optical head to the region 103b for recording the data b. When this second seek is completed, the stored data quantity has reached the maximum value B in as shown FIG. 3.
After the optical head reaches the region 103b, the data stored during the seek period 303 is recorded, as well as the data b, in the period 304. The data is recorded at a faster sped than the data generating sped, and therefore the quantity of data stored in the semiconductor memory decreases. Eventually, the stored data quantity is close to zero, and thereafter the data is recorded almost immediately after it is generated.
During the period 305, a seek operation for recording the data c is performed, as in the seek period 302 for the data b. During the period 305, data recording on the disc is impossible, and therefore all of the generated data is temporarily stored in the memory and the stored data quantity increases.
As in the period 304 for recording the data b, the data stored during the seek period 305 is recorded, as well as the data c, in the next period 306. The data is recorded at a faster speed than the data generating speed, and therefore the quantity of data stored in the semiconductor memory decreases. Eventually, the stored data quantity is close to zero, and thereafter the data is recorded almost immediately after it is generated.
As described above, in the case where control adjustments are performed during the repeated seeking and recording, the conventional apparatus requires a semiconductor memory having a capacity larger than the data generated during the maximum seek duration and the data generated during the control adjustment, in order to achieve real time, continuous reading of AV data without interruption.
In FIG. 3, the maximum value of the data stored in the memory is represented by reference numeral B. For example, when the maximum seek duration is one second, the control adjustment period is one second, and the data generating speed is 10 Mbps, the value B will be 20 Mbit. Therefore, in order to perform a control adjustment during a seek operation, the semiconductor memory has to have twice the capacity that is needed when only the seek operation is performed.
Accordingly, in the case where the control adjustment is performed during the reproduction/recording of real-time data such as a TV program, the conventional apparatus requires a large capacity semiconductor memory for temporarily storing the reproduction/recording data generated during the control adjustment process, in order to prevent an interruption to AV data reading for recording or reproduction during the period required between the start and the end of the control adjustment (i.e., a few seconds or more).
According to one aspect of this invention, a control adjustment method for adjusting a control of a recording/reproduction apparatus for a disc-shaped recording medium is provided, wherein the control is adjusted in response to an environmental change inside the recording/reproduction apparatus, such as a temperature change, the control adjustment method including the steps of: requesting an execution of the control adjustment; determining whether to inhibit or approve the execution of the control adjustment; and executing the control adjustment in the case where the execution of the control adjustment is approved in the step of determining the execution of adjustment.
In one embodiment of the invention, the disc-shaped recording medium includes a plurality of recording regions provided thereon. Audiovisual data is recorded in the plurality of recording regions by an optical head. A seek operation is performed during a recording or reproduction of the audiovisual data, such that in the seek operation the optical head moves between the plurality of recording regions. In the step of determining the execution of the control adjustment, the execution of the control adjustment is inhibited during a predetermined period of time after the execution of the seek operation.
In one embodiment of the invention, the recording medium includes a plurality of recording regions provided thereon. Audiovisual data is recorded in the plurality of recording regions by an optical head. A seek operation is performed during a recording or reproduction of the audiovisual data, such that in the seek operation the optical head moves between the plurality of recording regions. In the step of determining the execution of the control adjustment, the execution of the control adjustment is inhibited in the case where a seek operation is expected to occur within a predetermined period of time from the moment of determination.
In one embodiment of the invention, the occurrence of the seek operation is expected base on: a file management information regarding a recorded location of the audiovisual data on the recording medium; and the location where the current recording/reproduction is being performed.
In one embodiment of the invention, the recording/reproduction apparatus includes a memory section for temporarily storing audiovisual data for recording/reproduction. In the step of determining the execution of the control adjustment, an inhibition or approval of the execution of the control adjustment is determined based on a quantity of data stored in the memory section during recording/reproduction.
In one embodiment of the invention, the control adjustment is inhibited during recording, in the case where the quantity of the data stored in the memory section is equal to or more than a predetermined first data quantity.
In one embodiment of the invention, the control adjustment is inhibited during reproduction, in the case where the quantity of the data stored in the memory section is equal to or less than a predetermined second data quantity.
In one embodiment of the invention, the execution of the control adjustment is requested in the step of requesting adjustment when it is detected that there is an internal temperature change of the apparatus from a previous execution of the control adjustment by a predetermined temperature difference or more.
In one embodiment of the invention, the adjustment executing step includes: the steps of adjusting laser power during recording; and adjusting focus position during reproduction.
According to another aspect of this invention, a recording/reproduction apparatus is provided, the recording/reproduction apparatus including: a recording/reproduction section for recording/reproducing audiovisual data on a disc-shaped recording medium; a memory section for temporarily storing audiovisual data for recording/reproduction; an adjustment request section for outputting an adjustment request for executing control adjustment; an adjustment determination section for determining whether to inhibit or approve the execution of the control adjustment, and outputting an instruction indicating inhibition or approval; and an adjustment execution section for executing the control adjustment in the case where the instruction indicating approval is received.
In one embodiment of the invention, the recording medium includes a plurality of recording regions provided thereon. Audiovisual data is recorded in the plurality of recording regions by an optical head. A seek operation is performed during a recording or reproduction of the audiovisual data, such that in the seek operation the optical head moves between the plurality of recording regions. The adjustment determination section outputting an instruction indicating inhibition of the execution of the control adjustment during a predetermined period of time after the execution of the seek operation to the adjustment execution section.
In one embodiment of the invention, the recording medium includes a plurality of recording regions provided thereon. Audiovisual data is recorded in the plurality of recording regions by an optical head. A seek operation is performed during a recording or reproduction of the audiovisual data, such that in the seek operation the optical head moving between the plurality of recording regions. The adjustment determination section inhibits the execution of the control adjustment in the case where a seek operation is expected to occur within a predetermined period of time from the moment of determination.
In one embodiment of the invention, the occurrence of the seek operation is expected based on: a file management information regarding a recorded location of the audiovisual data on the recording medium; and the location where the current recording/reproduction is being performed.
In one embodiment of the invention, an inhibition or approval of the execution of control adjustment is determined based on a quantity of data stored in the memory section during recording/reproduction.
In one embodiment of the invention, the control adjustment is inhibited during recording, in the case where the quantity of the data stored in the memory section is equal to or more than a predetermined first data quantity.
In one embodiment of the invention, the control adjustment is inhibited during reproduction, in the case where the quantity of the data stored in the memory section is equal to or less than a predetermined seconds data quantity.
In one embodiment of the invention, the adjustment request section outputs a request of adjustment when it is detected that there is an internal temperature change of the apparatus from a previous execution of the control adjustment by a predetermined temperature difference or more.
In one embodiment of the invention, the adjustment execution section performs adjustment of laser power during recording and adjustment of focus position during reproduction.
Thus, the invention described herein makes possible the advantages of (1) providing a control adjustment method achieved with a small capacity semiconductor memory during real-time data reproduction/recording, and (2) providing a reproduction/recording apparatus capable of performing such a control adjustment.